Method of making welded blade structures



Oct. 6, 1953 E. D. HOESCH ET Al. 2,554,143

METHOD oF MAKING WELDED BLADE STRUCTURES Filed Aug. 24, 1949 AF j 33 lll J5 u J4 A Si /4 L I ff 5 \\\f T /6 Ill J5 34 Patented Oct. 6, 1953 METHOD F MAKING WELDED BLADE STRUCTURES Elmer D. Hoesch, West A ters, Milwaukee, Wis., c Chalmers Manufacturing Company, Milwaukee, Wis., a corporation of Delaware Applioauon August 24, 1949, serial No. 112,042 4 claims. v(o1. zia-156.8)

This invention relates generally to assemblies mbodying cast or weld metal joints and ,more partciularly to the methods and means `for-securing blades to a turbine disk or the like. The principal object of thefin'vention is to provide new and improved methods and means for the attachment of metal elements by welding to provide an integral article. Y

In a. broad aspect the invention resides in the art of attaching elements by a welded joint and is speciiically directed to methods ,and means for preventing relative movement of the elements during the welding operation, and to methods and means for arranging the elements prior to the welding operation to prevent high stresses and to lessen the tendency of cracking in the weld after the weld metal cools.

Another .object of this invention is to provide new and improved methods and means for preventing relative movement, yduring the welding operation. between elements which -are to be attached by welding .to form an integral article.

Another object is to provide new and improved methods and means for preventing relative movement, duringthe welding,r Operation, between elements which are to be attached by welding to form an integral article in instances where it `is impracticable to apply mechanical clamping means to said elements.

Another object is to provide new .and .improved methods and means for preventing relative movement, during the welding operation, between elements which are to be attached by welding to form an integral article in such a manner that the clamping pressure may be evenly distributed over substantially .the entire element desired restrained. Y

Another object is Lto provide new and improved methods and means for preventing relative movement, .during the welding operation, between a disk and blades which are to be attached thereto by welding.

Another object is .to provide new and improved methods and means for preventing .relative movement, during the welding operation, between a disk and blades which are to be attached thereto b y welding in instances where witis impracticable to apply conventional mechanical clampingmeans to said blades.

Another .object Ais to provide new and improved methods `and :means for preventing relative movement, during the welding operation, between a disk .and 'blades which are to be attached thereto `by welding such that the clamping pressure maybe evenly distributed over substantially the entire surface of Yeach blade.

uis, and notorio. Matassignors to Allis- Another object is to provide a method of welding which reduces the tendency o f a crack to extend into a Weld between members whose adjacent surfaces .form such crack.

Another object is to provide a method of weming which prevents excessive internal stresses from occurring where the joint between adjacent elements terminates in a weld which connects these elements to a support member.

,Another object is to provide in connection with the attachment of blades to a disk by Welding a method which reduces the tendency of radial intorblade extensions from extending into a weld between adjacent blade bases- Another object isL to provide in connection with the attachment -DI blades to a disk a method which prevents. high internal stresses from occurring where the joint between adjacent blade bases terminates in a Weld which Secures the blade bases to the disk rim.

Other objects will appear hereinafter as the description Of. the invention proceeds. Y

The `z ,iovel features of theV invention and how the objects are attained will appear more fully from this specification and the accompanying drawings showing one embodiment of the invention `and forming a part of Vthis application, and all these novel features are intended to be pointed out in the claims.

In the drawing: n

1 is a side elevation of a blade which is susceptible of beiner attached to a disk by the employment ofthe invention;

. Fig. A2 is an end elevation o f the blade shown inlfiali Fig. 3 isa section showing ythe blades placed in a fixture which may be Vused in the manu- `facture `of a bladed rotor in Aaccordance with the disclosed'method;

Fig. 4 is .a section similar to Fig. 3 showing the disk and blades in clamped position ready for welding the -rlst side;

`5 -isa section similar to Fig. 3 except that the disk and jblad'es are inverted in prepa-ration for welding ofthe second side;

Fig. 6 is a sect-ion similar to Fig 4 except'that the ,disk and blades are clamped in an inverted pic'isitio'n` in praparationgfor welding .the second s dei' A Fig. '7 ls a plan view of the disk, -blading, and fixture vshowing a 'keyway for inserting-the last blade and' spacers between the blade bases; vand Fig 8 is the Vcompleted .disk 'and blade' assembly. 1 l Y `llteferririg to the' drawing for'ah example Aof oney yof the many arrangementsV which may 'be' si welded in accordance with this invention, Figs. l and 2 show an element or blade I0, a plurality of which is to be attached by welding to a support member or disk II, as shown in Fig. 8. In this instance a blade base I2 has a weld preparation contour I3 which'is complementary to a weld preparation contour I4 (see Fig. 4) on the rim of the disk II; it is to be understood, however, that any suitable method of preparing the surfaces of the respective elements for attachment by welding may be utilized.

In Figs. 3, 4, 5, 6 and 7 is illustrated a fixture I5 which may be used in manufacturing a bladed rotor in accordance with this invention. The fixture I5 comprises a base member I6 of suitable diameter having annular locatingV surfaces for positioning the blades l and the disk II; the locations of these surfaces being determined in each case by the size and shape of the elements 4to be positioned in the fixture.` Fig. 3 'shows the blades I0 stacked in the fixture I5, in preparation for welding the first side, with the blades being `axiaily located by a surface I'I and an annular rib I8 and radially located by an annular vertical surface 20.

The blades I0, in this instance, have blade bases I2 of the offset type as shown in Fig. 2. A keyway 2I (Fig. 7) is provided in the base member IS and the last blade in the row is placed in position through the keyway. A key 22, having its top surface flush with the top surface of the base member I5, s provided and said last blade is driven tightly into position causing the complete blade ring to tighten against surface 2d. The key 22 is then secured in the keyway 2l by means of lcap screws 23.

A plurality of spacer blocksV 24 are secured to the base member I6 by means of dowels 25 and are located radially outward from the blades I0 land in crcumferentially spaced relation. In such position the plane 26 of the upper surfaces of the blocks 24 is slightly higher than the plane of the upper Surfaces 21 of the blade bases I2. Fluid retaining means, herein shown as a thin steel annular dam 30, is placed completely around the blades I0 in the space between the tips of the blades and the spacer blocks 24. The height of the dam 30 is slightly less than the height of the blocks 24.

As shown in Fig. 4, the disk I I is axially located on the armular surface I'I of the base member i and secured thereto by means of a bolt 3i, which extends through a hole 32 in the disk and is threaded into the base member, thereby positioning the disk in welding relation to the blades m, The region surrounding the blades ID between the blade .bases I2 and the dam 30 is filled so as to overflow with ya flowable solidifiable material 33, in this instance characterized by a slurry (consistency of thick cream) of gypsum cement with a setting expansion rate of .0005 per inch, a setting time cf sixteen minutes, and a compres--` sive strength of 4500 p. s. i. when dry. The annular rib I8, upon which the blade IIJ is axially located, permits the material 33 to iiow beneath the blades such that the blades are substantially 4surrounded on all sides by such material. Prior to the solidiiication of material 33 an annular cover member 34 is secured to the spacer blocks 24, by means of bolts 35 which are threaded into the base member I6, such that a portion of the underside of the cover engages the surfaceof the material 33. It is important that the cover member 34 be in fixed lrelation to the base member I6 but does not necessarily have to be attached as shown. It is to be noted that in this instance a lip 36 on the inside diameter of the cover 34 bears on the upper surfaces 21 of the blade bases I2 causing a turning moment on the blades Ii! forcing them against the rib I8. It is to be understood, however, that the cover member 34 with the lip 36 or other equivalent mechanical means for clamping the blades I0 to the base member I5 may be omitted in which case material 33 alone would be relied on to perform the clamping function.

After the cover member 34 is in place and the material 33 has been allowed to set, the fixture is preheated to a specified temperature for welding and the first side is then welded in any known manner. The fixture is allowed to cool and the material S3 is subsequently chipped from the blades I0.

Preparationvfor welding of the opposite side is made in 'accordance with Figs. 5 and 6 but it is to be understood that in some cases it may be satisfactory to weld only on one side and it is obvious thatthis, invention is applicable to such constructions also. In the present instance the same base member I6 may be used for welding the opposite side and a's the blades I0 are now attached, the disk I I with the attached blades is inverted and placed in the fixture I5 as shown in Fig. 5. A base ring 31, positioned concentrically on the surface I1 of the base member I6, is provided to axially locate the disk II 'and the -disk is attached concentrically to the base member by means of the bolt 3| which extends through the hole 32 in the disk and is threaded into the base member. The addition of the .base ring 3'! makes it necessary to add an equivalent height to the spacer blocks 24 and this is done by means of spacer washers 40 and 4I. A thin steel dam 42 is placed on the fixture I5 as before, but this time the height thereof is to be slightly less than the height of the spacer blocks 24 and the added spacer washers 40 and 4I. A slurry of the material 33 is again prepared and the region between the blade bases I2 and the dam 42 is filled to overflowing as before. The cover member 34 is secured in place as before except that the spacer washers 40 'andAI now separate the cover member from the spacer blocks 24. As in preparing the first side for welding, the lip 36 or another equivalent mechanical means for clamping the blades Il! to the base member I5 may be omitted. After the material 33' has been allowed to set a second annular weld preparation contour 43 is machined between the rim of the disk II and the blade bases I2 on'the side opposite the first weld 44, as shown in Fig. 6:. The fixture I5 is then preheated to a specified temperature for welding and the second side is then welded in any known manner. The fixture is allowed to cool and the material 33 is subsequently chipped from the blades I0.

Another feature of the invention is to provide means for preventing excessive internal stresses from occurring where the joint between adjacent elements terminates in a weld which connects these elements to a support member and also to reduce the tendency of the space between these elements from extending into the weld during cooling thereof, after the welding operation. In the attachment of metal elements by welding to provide lan integral article, wherein a plurality of elements having adjacent sides abutting each other and whichare to be joined at their ends to a support member, there is a fundamental probassaut lem wherein an excessive strain 'ls imposed on the cooling weld by the contractionof the lelen'lents which often causes theweld'metal toer-ack. The invention provides fa solution 'to this problem 'and although Isuch solution will be illustrated (see Fig. 7) in connection with the attaching of blades to a disk it is to be understood that it also has a more general application in 'the attachment off various other types of elements by welding.

Knowing the dimensions of the blade bases I2, the coeiiicient of vlinear expansion of the kind of metal of which the blades are composed, and the welding temperature, it is possible to calculate the actual linear 4'ex`1'a'ansion in a circumferential direction of 'each blade base as the temperature increases -from room temperature to welding temperature. The width of the blade bases I2 is selected and the blades are so stacked around the rm'of the disk lII -such that a space is provided between each of the blade bases somewhat greater than `the above mentioned actual linear expansion of each of theA blade bases. The means for providing a space between eac-h of the blade bases 'I2 is herein characterized by spacers 5S composed of a material which permits spacing of the blade bases upon stacking lin the fixture I5 but which readily compresses to permit expansion of the blade bases in a circumferential direction. rIhe effect of such spacing is that expansion of the blade bases I2 does not entirely close the space between them and thus permits the weld metal to bridge this .residual gap between the blade bases. It 1s clear that where such a residual gap is not provided for, a radial crack mus-t develop and progress into the weld, upon contraction y.of blade bases I 2, until the elastic deformations and local yielding reduce the stress to an acceptable limit. However, Where a residual gap exists after eX- pansion of the blade bases I2 it is seen that the length of weld metal across such gap will be circumferentially extended upon contraction of the blade bases but it is obvious that the internal strain and tendency to crack is much less than the case where the blade bases are close fitted vi.

and no weld metal exists between the blade bases prior to contraction of the blade bases. To 1llustrate further, with an example, assume that the width of each blade base I2 expands 0.002" and that a 0.010" spacer 50 is provided upon stacking between each of the blade bases. The assumed 0.002" expansion leaves residual a gap of 0.008 between the blade bases I2 and the weld metal bridges this gap. When the blade bases I2 cool the contraction requires 0.002" extension of the 0.008 length of the weld across the separation. This requirement of 25% extension in a circumferential direction results 1n less internal strain in the weld and less tendency to crack the weld than in the case of the close fitted blades where only a negligible amount of weld metal between the blade bases is subgected to this circumferential extension` upon contraction of the blade bases.

Various means may be used for spacing the blade bases I2 such as inserting spacers 50 having the proper thickness between the blade bases. An electrical insulation liber, often called .sh paper, which is made in various degrees of thickness and has a paper-like substance 1s. one example of a type of spacer which gives satisfactory results. n

A bladed rotor fabricated by msertlng spacers 50 of the proper size between the blade bases upon stacking, as described above, may be disperature and noting,

'method for the tingulshed from a bladed rotor/'where Vthe blade bases are originally fclose fitted. This distinction may be -seen the iinished rotor by calculating the contraction of the width of `a blade base from welding temperature to room temby physical measurement, that the 'widths of the :spaces between the blade bases are. respectively greater than the calculated contraction `or the blade bases. In the case of close fitted blade bases the spaces therebetween will be respectively Iequal to the calculated contraction. Thus, in this respect, a bladed rotor fabricated' according to .my method differs physically from :a bladed rotor which does not provide such spacing means between the blade bases upon stacking.

From the foregoing it will be apparent to those skilled in the art that the illustrated embodiment vof the invention provides a new and novel attachment of metal elements by Welding to provide lan integral article, and accordingly, accomplishes the objects of the invention. lOn the other hand, .it will also be obvious to those skilled in the art that the illustrated embodiment of the linvention ymay be variously changed and modified, or features thereof, singly or collectively, embodied in other combinations 'than those illustrated without departing from the spirit of the invention andaccordingly the disclosure herein is illustrative only,

yand the invention is 'not limited thereto.

It is claimed and Patent:

.1.. The method of making a bladed element for turbines and the like comprising the steps of 'placing 'a circumferential row of blades around a rotor 'disk with the base portions lof said blades and the rim portion of said disk cooperating to denne an annular weld receivable contour, providing liquid retaining means in cooperable relation to said blades to enclose an area to` receive and retain a slurry in engagement with said blades except in a zone about said weld receivable contour, applying a slurry of solidifiable material in said enclosed area cooperable with said blades upon solidirlcation of said material to seize and hold said blades in position pending the application and freezing of weld metal to said weld preparation contour, applying weld metal to said weld receivable contour after said material solidines, and then removing said material after said weld metal freezes.

2. The method of making a bladed element for turbines and the like comprising the steps of placing a circumferential row of blades around a rotor disk with the base portions of said blades and the rim portion of said disk cooperating to denne `an annular weld receivable contour, providing liquid retaining means in cooperable relation to said blades to enclose an area to receive and retain a slurry in engagement with said blades except in a zone about said weld receivable contour, applying a slurry of gypsum cement in said enclosed area cooperable with said blades upon solidication of said cement to seize and hold said blades in position pending the application and freezing of weld metal to said weld preparation contour, applying weld metal to said Weld receivable contour after said cement solidilies, and then removing said cement after said weld metal freezes.

3. The method of welding blades to a rotor disk for 'turbines and the like comprising the steps of placing on a base member a rotor disk and a circumferential row of blades around said rotor desired vto :secure by Letters disk with the base portions of said blades and the rim portion of said disk cooperating to dei-lne an annular Weld receivable contour, providing liquid retaining means in cooperable relation to said blades to enclose an area to receive and retain a slurry in engagement with said blades except in a zone about said Weld receivable contour, applying a slurry of solidiable material in said enclosed area cooperable With said blades upon solidication of said material to seize and hold said blades in position pending the application and freezing of weld metal to said Weld preparation contour, applying prior to the solidication of said material a cover member such that a portion of the under side of said cover member engages the surface of said material and another portion of the under side of said cover member bears on at least a portion of said blades to cooperate with said material to hold said blades rigidly in position, applying Weld metal to said weld receivable contour after said material solidiiies, and then removing said cover member and said material after said weld metal freezes.

4. The method of welding blades to a rotor disk for turbines and the like comprising the steps of placing on a base member a rotor disk and a circumferential row of blades around said rotor disk With the base portions of said blades and the rim portion of said disc cooperating to define an annular Weld receivable contour, providing liquid retaining means in cooperable relation to said blades to enclose an area to receive and retain a slurry in engagement with said blades except in a zone about said weld receivable contour, applying a slurry of gypsum cement in said enclosed area cooperable with said blades upon solidiication of said cement to seize and hold said blades in position pending the application and freezing of Weld metal to said Weld preparation contour, applying prior to solidication of said cement a cover member such that a portion of the under side of said cover member engages the surface of said cement and 'another portion of the under side of said cover member bears on at :least a portion of said blades to cooperate With said cement to hold said blades rigidly in position, applying weld metal to said weld receivable contour after said cement solidies, and then removing said cover member and said cement after said weld metal freezes.

ELMER. D. HOESCH. ROBERT G. MATTERS.

References Cited in the iile of this patent UNITED STATES PA'IENTS Number Name Date 901,960 Farquhar Oct. 27, 1908 1,510,146 Johnson Sept. 30, 1924 1,551,342 Steenstrup Aug. 25, 1925 2,090,468 Brown Aug. 1'7', 1937 2,201,037 Hagenmeyer May 10, 1940 2,380,276 Warren July 10, 1945 2,384,919 Huber Sept. 18, 1945 2,392,281 Allen Jan. 1, 1946 2,405,146 Huber Aug. 6, 1946 2,450,493 Strub Oct. 5, 1948 2,454,580 Thielemann Nov. 23, 1948 2,504,823 George Apr. 18, 1950 FOREIGN PATENTS Number Country Date 9.721 Great Britain May 5, 1908 

